title: A user-friendly Matlab program and GUI for the pseudorotation analysis of saturated five-membered ring systems based on scalar coupling constants.
abstract: BACKGROUND
  The advent of combinatorial chemistry has revived the interest in five-membered heterocyclic rings as scaffolds in pharmaceutical research. They are also the target of modifications in nucleic acid chemistry. Hence, the characterization of their conformational features is of considerable interest. This can be accomplished from the analysis of the 3J(HH) scalar coupling constants.
  
  
  RESULTS
  A freely available program including an easy-to-use graphical user interface (GUI) has been developed for the calculation of five-membered ring conformations from scalar coupling constant data. A variety of operational modes and parameterizations can be selected by the user, and the coupling constants and electronegativity parameters can be defined interactively. Furthermore, the possibility of generating high-quality graphical output of the conformational space accessible to the molecule under study facilitates the interpretation of the results. These features are illustrated via the conformational analysis of two 4'-thio-2'-deoxynucleoside analogs. Results are discussed and compared with those obtained using the original PSEUROT program.
  
  
  CONCLUSIONS
  A user-friendly Matlab interface has been developed and tested. This should considerably improve the accessibility of this kind of calculations to the chemical community.
authors.affiliation: NMR and Structure Analysis Unit, Ghent University, Ghent, Belgium. pieter.hendrickx@ugent.be
authors.forename: Pieter M S
authors.initials: PM
authors.lastname: Hendrickx
authors.forename: José C
authors.initials: JC
authors.lastname: Martins